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Profitability Is Aim Of Crossover Jets’ Better Maintainability

Among the various costs involved in running an airline, MRO (maintenance, repair and overhaul) on average accounts for 10%, according to the International Air Transport Association’s (IATA) World Air Transport Statistics 2017. Each new aircraft or upgrade of a type aims to make that cost lower.

Crossover narrowbodies—whose capacity falls between regional aircraft and the single-aisle industry workhorses of the Boeing 737 and AirbusA320 families—were almost all developed from clean-sheet designs, giving them the opportunity to have maintainability “designed in.” Even the one exception, the EmbraerE-Jets E2 family, which has the same fuselage as its first-generation predecessor, has so many changes “under the skin” that the company has been able to implement substantial cost-cutting measures in this area as well. Moreover, Embraer was able to develop those improvements by learning from the earlier models.

Jabour Nelson, deputy head of customer support at Mitsubishi Aircraft Corp., emphasizes that lower-cost maintenance was a key goal for the MRJ’s design team. “Absolutely, yes,” he declares. “The aircraft was designed from inception with maintainability and owner/operator reduced direct maintenance cost (DMC) in mind. These are prevalent throughout the entire aircraft and its maintenance programs. The direct results are reductions in cost and more effective maintainability across the board.”

A good example is the MRJ Aircraft Maintenance Program. “This was designed to provide operators with a substantial decrease in scheduled maintenance costs and extended aircraft in-service operations with maintenance intervals of 750 flight hours per A check and 7,500 flight hours per C check. Other OEMs’ aircraft began their service lives at 600 and 6,000-flight-hour intervals, respectively,” Nelson says.

At Embraer, Carlos Barra, the director of technical support engineering, notes that the Brazilian manufacturer’s experience in developing several programs in recent years helped considerably, with a set of maturity tools being used to expedite product reliability. “Endurance tests, highly accelerated life tests, system simulations, virtual aircraft to integrate systems, software monitor reviews, intensive use of lab and rig tests were all put in place,” he recalls. “The paradigm ‘test to pass’ was forgotten and replaced by a new one: ‘Test to Fail, and Fix It! Then test to fail and fix it again and again.’ The philosophy was ‘better to fail by Embraer’s hand than by the customer’s’, [with time to spare]to fix before delivering aircraft.”

The maintenance and aircraft operations specialist team took part in the E-Jets E2 development to guarantee the product would deliver high-quality standards on aircraft availability, low maintenance cost and ease of operation. This was aided during the flight-test campaign by the Embraer Pioneer Airlines program, based at the Gaviao Peixoto facility.

“Embraer Pioneer Airlines has three different objectives, one of which is to prepare and mature the aftermarket support organization to deliver a smooth entry into service,” Barra says. “E-Jets E2 flight tests will involve more than 100 hr. of dedicated maturity flights, apart from function and reliability flight tests, simulating specific conditions of an [airline] operation, which are not covered by standard commercial aircraft certification.”

Before reaching a stage such as Pioneer Airlines, digital mockups and virtual reality were used to help realize the planned accessibility to components and replaceable units. “A team of engineers with maintenance knowledge and experience analyzed the market’s maintenance requirements, taking into account previous developments,” Barra notes. “This team and the design team worked [to provide] an optimized aircraft in terms of maintenance. To achieve all maintenance goals, more than 7,000 worker hours were invested in digital mockups and virtual reality during integrated maintainability zonal analysis meetings to have the planned accessibility to components and replaceable units.

“Using these tools to evaluate maintainability aspects was essential, because they helped designers and engineers to identify design, maintenance and assembly issues in advance and to study alternative solutions before manufacturing started,” Barra explains. “These tools contributed to a significant reduction in equipment and tooling necessary for maintenance procedures, and in the equipment/component mean-time-to-repair, which means higher aircraft availability, lower DMS and higher schedule reliability.”

A similar story can be found at Mitsubishi. “The MRJ design has undergone thousands of hours of Catia/3D and human-interface modeling to ensure ease of systems access,” Nelson says. “Maintainability is embedded in the entire aircraft design, providing maintenance cost reductions with the customer in mind.”

Nelson points out that the Pratt & Whitney PW1200G engine also has enhanced maintainability features. “The engine has an increased life-limited part (LLP) life-cycle limit up to 25,000 cycles, which is 25% better than other OEMs’ products at 20,000 cycles and therefore reduces costs,” he says. “The Fan Gear Drive Systems have no LLP limit. This translates to lower cost per cycle and extended ‘on-wing’ operations and increased performance for the MRJ owner/operator,” he contends.

Of course, with PW1500G engines on the Airbus A220 and PW1700G/1900G on the Embraer E2s, similar maintainability benefits are likely to accrue on those types.

Although Mitsubishi does not have the equivalent of a Pioneer Airlines program, it does encourage customer participation in the MRJ flight-testregimen, allowing unprecedented aircraft access. “This creates dynamic feedback whereby the customer can directly interact with Design Engineering [about] findings and [discuss] improvements in maintainability and reliability,” Nelson explains. “In [keeping] with the Japanese kaizen [change for the better] philosophy, we will continually improve the maintainability of the MRJ throughout its life cycle,” he vows.

Getting the message across about the improved maintainability of crossover narrowbody jets is important if the type is to win a bigger market share. Embraer’s Barra can point to renegotiated supplier deals—even when the incumbent supplier won the bid—which, coupled with longer heavy-check intervals, have reduced DMCs by 25%, compared with current E-Jets.

“E-Jets E2 scheduled maintenance has a 1,000-flight-hour interval for intermediate [A] checks and 10,000 interval for heavy [C] checks. Also, the heavy-check basic inspection downtime has been reduced by 15% compared with the E1,” Barra notes. “There are no out-of-phase tasks in the E2 maintenance plan and corrosion prevention and control program activities are only required every eight years with fewer tasks (now 82, down from 240) when compared to E-Jets E1.”

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